You mean routing.yml? It's the same as in the sandbox project.
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DziamidJan 30 '12 at 10:42

I've expanded on this answer here: gist.github.com/3226510, you can now pass just the object through instead of an array i.e. path('route', entity) (should be BC). Also, after checking for a matching key the router will explode the key by _ to check across relations, i.e. parent_slug would resolve to $object->getParent()->getSlug().
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SteveAug 1 '12 at 12:47